Ultra broad band base station antenna systems typically operate in the 690-960 MHz (“Low Band”—LB) and 1.7-2.7 GHz (“High Band”—HB) spectrum which includes most cellular network frequency bands used today. With the growing demand for a deeper integration of antennas with Radios, e.g. Active Antenna Systems (AAS), new ways of designing ultra compact ultra broadband multiple arrays base station antenna architectures are being requested without compromising the antenna key performance indicators (KPIs). For those architectures the coexistence of multiple LB and HB arrays is a key technical point. As it is well known, this becomes even more challenging when trying to reduce the overall geometrical antenna dimensions (compact design) and keeping RF KPIs. Among many other technical design strategies, one of the key points is the radiating elements design for the LB and HB arrays. Ideally they should be electrically invisible to each other. From this perspective the physical dimensions of the radiating elements are one of the dominating factors.
WO2008/017386 A1 describes an antenna arrangement, in particular for a mobile radio base station. The antenna arrangement comprises a reflector frame with a coupling surface which is capactively coupled to a ground plane.
WO2006/059937 A1 describes a dual band antenna with shielded feeding means.